数字信号光耦合器应用电路设计

Applied Circuit Design of Optoelectronic Coupler to the Digital Signal

较强的输入信号可直接驱动光耦的发光二极管,较弱的输入信号须经放大后才能驱动光耦。在光耦光敏三极管的集电极或发射极直接接负载电阻即可满足较小的负载要求:在光耦光敏三极管的发射极加三极管放大驱动,通过两只光电耦合器构成的推挽式电路以及通过增加光敏三极管基极正反馈,既达到较强的负载能力,提高了功率接口的抗干扰能力,克服了光耦的输出功率不足的缺点,又提高光耦的开关速度,克服了由于光耦自身存在的分布电容,对传输速度造成影响。最后给出了光耦合器在数字电路中应用示例。

The light-emitting diode of optocoupler can be directly drived by stronger input signals,the weaker the input signal can be enlarged before driving optocoupler.Connecting directly load resistance with the collector or emitter of phototransistor to meet smaller load requirements;drover by the amplifier triode on the emitter of phototransistor,push-pull Circuits consisting of two optocoupler as well as positive feedback added to base of the phototransistor not only achieve strong load capacity and enhance the power of the interface anti-jamming capability,but also overcome the shortcomings of the scant output power,increase the switching speed,overcome effect on the speed of the transmission due to the distribution of capacitance. Finally,the application example of the optocoupler in the digital circuit is given.